The principal objective of this proposal is to study the role of T cells in the IgA response. Initial studies of this reporting period were directed at understanding why lymphoctes which are isolated from murine mammary glands respond poorly in blastogenic assays. During this period, we observed that irradiated mammary gland cells suppress mitogen-induced spleen cell blastogenesis in dose-dependent fashion. The ability of irradiated mammary cells to suppress spleen cell blastogenesis suggests that the low stimulation observed with mammary gland cells may be due to some form of cellular suppression rather than technical problems with our technique for isolation of mammary gland lymphocytes. Experiments were directed at determining the mechanism of cell suppression. In these experiments we were able to reverse the effect mammary suppression of lymphocyte blastogenesis to 80% of controls with indomethacin. The mechanism of the indomethacin effect is now under investigation. T-cell hybrids have been generated from Peyers patches and peripheral lymph nodes. The peripheral lymph nodes were harvested five days after injection of Freund's adjuvant in the foot pads, and the two different protocols were utilized for the Peyers patch cells. Both protocols produce fewer clones than periperal lymph node T-cells; however, we have been successful in generating 11 Peyers patch T-cell hybrids and are currently in the process of cloning and examining the mechanism by which these cells trigger B-cells to produce immunoglobulin A in the mitogen-driven system. We plan to concentrate on the following goals for the upcoming year: (1) Characterize Peyer's patch T-cell hybrids effect on immunoglobulin production by B-cells; a) set up immunoglobulin isotope assay; (b) set up limiting dilution analysis; (2) Begin experiments to isolate antigen specific T-cells.